The invention relates to a flow sensor having a housing and a semiconductor chip with integrated sensor.
A known flow sensor of this type comprises a two part housing forming a measuring conduit. A semiconductor chip with a sensor is arranged at a wall of the measuring conduit. For sealing the conduit, the semiconductor chip is clamped between the housing sections.
This known solution has, however, the disadvantage that it is not suited for applications where there is a high static or dynamic pressure in the measuring conduit.
Hence, it is a general object of the invention to provide a flow sensor with a housing which is able to withstand high pressure.
Now, in order to implement these and still further objects of the invention, which will become more readily apparent as the description proceeds, the flow sensor is manifested by the features that it comprises a housing with at least two housing sections and forming a measuring conduit between at least some of said housing sections, a semiconductor chip comprising a sensor arranged at a wall of the measuring conduit, a sealing ring arranged between two housing sections and surrounding said semiconductor chip, said sealing ring pressing against a support formed by at least one of said housing sections, and at least one strip conductor connected to the semiconductor chip and extending between said support and said sealing ring and out of said housing.
In such an arrangement, the semiconductor chip has no sealing function but is completely arranged in the area enclosed by the sealing ring. For connecting the semiconductor chip, one or more strip conductors are lead out of the housing, passing between the support and the sealing ring. Such a device can be assembled easily.
Preferably, the at least one strip conductor is arranged on a flexible support foil. It is, however, also possible to arrange the strip conductor on one of the housing sections.
Preferably, the measuring conduit is formed by a groove in the surface of a first housing section. For connecting the groove, connecting ducts can be provided, e.g. in the form of bores or holes, which extend through one or several housing section(s). The sealing ring can be arranged around the groove. This arrangement allows to seal the conduit from all sides.
Preferably, the semiconductor chip is arranged in a recess of the second housing section and its top surface (i.e. the side with the sensor) is flush with the wall of the measuring conduit in order to favour laminar flow within the conduit. For exactly positioning the top surface of the semiconductor chip, it is in contact with the first housing section. Preferably, a spacer is arranged at the bottom of the recess, which spacer is deformed by the force exerted by the first housing section on the semiconductor chip. In this way, an accurate alignment of the sensor element with the measuring conduit is guaranteed when the device is assembled. The spacer can e.g. be formed by small bumps at the bottom of the recess.
The flow sensor according to the present invention is suited for measuring the flow of fluids at normal and elevated pressure.